Input impedance antenna automatic matching system

The paper presents a new design for an antenna input impedance automatic matching system. In order to achieve this main objective, it is necessary to accomplish several intermediate tasks. On the one hand, a study of the implementation of a generic electronically tunable impedance synthesizer is carried out. Then, a prototype based on the research is constructed, and its characteristics and improvements are evaluated. On the other hand, a fully automatic system is developed. The device is integrated inside a commercial mobile radio communications handset, in order to evaluate the improvements achieved with the automatic system. Experimental results about the influence of the human body on the input impedance of helical and monopole antennas are presented for the 380-400 MHz frequency band. Several control methods are studied.